This application claims the priority of German application 196 32 859.4 filed in Germany on Aug. 14, 1996, the disclosure of which is expressly incorporated by reference herein.
The invention relates to an operating device for a motor vehicle transmission of the type having a shift lever which, for shifting between transmission ratios, is movably mounted on the motor vehicle, particularly can be swivelled in one shifting channel respectively about a shifting axis essentially in the longitudinal direction of the vehicle, and, for selecting between different shifting channels in at least one selection channel can be swivelled about a selection axis essentially in the transverse direction of the vehicle, and which, by way of a motion gearing, is connected with at least one transmission control shaft of the motor vehicle transmission, a motor vehicle transmission case being linked to the motion gearing.
German Patent Document DE 26 58 274 B2 describes a bearing for a manual lever for a gearbox of vehicles in which the manual lever is connected with the gearbox by way of a motion gearing having a support rod and a shift rod. By way of a ball-and-socket joint and additional linkage members, the manual lever is movably connected in the shifting direction and the selecting direction with the vehicle floor as well as with the support rod. The bearing for the manual lever has the task of absorbing vibrations of the gearbox effectively in front of the manual lever while the construction of the suspension and bearing members is compact.
However, such a bearing can have a disadvantageous effect when the motor vehicle transmissions and the manual levers have, for example, an unfavorable position with respect to the driver's sitting position. Since movements of the motor vehicle transmission are transmitted by way of the motion gearing to the manual lever, this lever moves at different amplitudes depending on how long it is. This can impair the shifting feel for the driver and influence the driving comfort.
It is therefore an object of the invention to provide an operating device for a motor vehicle transmission in which case the motion gearing to the motor vehicle transmission is designed such that the shift lever maintains its position while the motor vehicle transmission can move in any direction with respect to the space.
According to the invention, this object is achieved by providing an operating device of the above noted type, wherein the shift lever is mounted on a vehicle part fixed to the vehicle body, and the motion gearing, in a projection onto a shifting plane, includes at least one parallelogram linkage of four rods, one rod being fixedly connected with the shift lever, and during a shifting and/or selecting movement of the shift lever, three rods being changed in their position, and one rod maintaining its position, which rod, on its one end, in the shifting plane being swivellably mounted on a vehicle part fixed to the vehicle body and, on its other end, being connected with the motor vehicle transmission case while being movable over at least so many degrees of freedom that each spatial movement of the motor vehicle transmission case is possible without causing reaction forces in the motion gearing, the rod which is fixedly connected with the shift lever maintaining its position and the other three rods being changed in their position.
According to the invention, the shift lever is movably mounted at least in the shifting and selecting direction on a vehicle part fixed to the vehicle body and, viewed in the projection onto the shifting plane, the motion gearing to the motor vehicle transmission includes at least one parallelogram linkage consisting of four rods, one rod being fixedly connected with the shift lever and, during a shifting and/or selecting movement of the shift lever, three rods being changed in their position and one rod maintaining its position. On its one end, this rod is swivellably in the shifting plane mounted on a vehicle-body-fixed vehicle part and, on its other end, is connected movably by at least so many degrees of freedom with the motor vehicle transmission case that any spatial movement of the motor vehicle transmission case is possible without causing reaction forces in the motion gearing. In the case of a spatial movement of the motor vehicle transmission case, that rod will then maintain its position which is fixedly connected with the shift lever and the other three rods are changed in their position.
An operating device of this type for a motor vehicle transmission has the advantage that the shift lever can be mounted anywhere on the body of a vehicle. As a result, its length is independent of the driver's sitting position even if this sitting position has, for example, a larger vertical distance from the transmission, as for example, in the case of vans or trucks. A relatively short shift lever can be mounted in this manner in the driver's proximity and, during its operation, the motion gearing transmits the movements at the ratios selected in the case of the construction in the selecting and shifting direction to the motor vehicle transmission. In this case, the shift lever is disposed free from vibrations and is uncoupled from all spatial movements and vibrations of the transmission line relative to the vehicle body. Even when a shift lever is very long, no movement of the shift knob of the shift lever takes place during a movement of the vehicle transmission relative to the vehicle body.
In preferred embodiments of the operating device, the three rods of the parallelogram linkage which are changed in their position during a shifting and/or selecting movement of the shift lever, viewed in a projection onto the shifting plane, are the shift lever between the shifting axis and a first connection joint to a coupling element; the coupling element between the first connection joint and a second connection joint to a connection element; and the connection element between the second connection joint and a third connection joint to a fourth rod, the holding element. In this case, the rod of the parallelogram linkage which maintains its position during a shifting and/or selecting movement of the shift lever is formed by the fourth rod, between the third connection joint and the axis of rotation of the shift lever in the shifting direction. On its one end, the fourth rod is swivellably about a fastening axis linked to a vehicle part fixed to the body and, on its other end, is rotatably in all directions mounted on the connection element, the axis of rotation of the shift lever in the shifting direction and the fastening axis, when the shift lever is not deflected into the selecting direction, extending coaxially. Furthermore, from the other end of the fourth rod, the connection is established to the motor vehicle transmission case by means of a support rod.
Advantageously, the connection element consists of an angle lever whose end of a first leg is swivellably connected with a shift rod and whose end of a second lever is movably connected with the coupling element such that the selecting movement as well as the shifting movement of the shift lever is transmitted to the shift rod by way of the coupling element and the angle lever. In a particularly advantageous embodiment of the invention, the angle lever is mounted on the holding element by way of a ball-and-socket joint.
In a particularly simple embodiment, the support rod to the motor vehicle transmission case is swivellably mounted on the fourth rod, the swivel axis extending through the center point of the ball-and-socket joint. In this case, the fourth rod as the holding element consists of two holding element parts which are connected by a joint such that they can be rotated with respect to one another about the longitudinal axis of the holding element.
In another preferred embodiment of the invention, the coupling element is to be constructed in a simple manner if it consists of two coupling rods which, together with the shift lever and the connection element, form a four-bar mechanism in a plane perpendicular to the shifting plane, in which case at least two members of the four-bar mechanism--the shift lever and the connection element--are guided in parallel to one another. By way of the length of the two coupling rods, the ratio of the motion gearing can advantageously be influenced in the selecting direction. It can be selected to be equal to, larger or smaller than the ratio in the shifting direction and is therefore independent of it. In this case, the fourth rod--the holding element--extends in parallel to the plane of the four-bar mechanism.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.